Crews are searching for the vessel by air and sea near its last known location, navy spokesman Enrique Balbi told reporters.

“We have ordered all terrestrial communication stations along the Argentine coast to carry out a preliminary and extended search of communications and to listen in to all the possible frequencies of the submarine,” the navy said in a statement Friday.

The vessel had been traveling from far southern Argentina’s Tierra del Fuego archipelago to its home base in Mar del Plata, a coastal city hundreds of miles to the northeast.

“The submarine knows that if it does not have communication with land for this long, it has to surface,” Balbi said.